I can’t judge the accuracy of this list, not having seen any of the finale episodes. (In fact, I have never seen a single episode of 12 of the 15 shows.)
The very worst series finale of all time, though, was that of “Twin Peaks”.
Gotcha beat. I haven’t seen a single episode of 13 of the 15. Only watched a couple seasons of “House of Cards” and quit after it went way off the rails. I did watch “Mad Men” from beginning to end and thought the ending WAS rather dopey.